1. Field of the Invention
This invention relates to an electrical switch for controlling lights or other appliances, of the type which can exercise control in a preprogrammed manner to turn controlled equipment on and off automatically in a manner simulating normal manual usage of a switch controlling the device.
2. Review of the Art
Switches with such a capability are widely utilized, both for security purposes in order to turn lights on and off in a manner such as to provide an appearance that premises in which the switch is installed are occupied, or to turn lights or appliances on for preprogrammed periods each day.
Typically such switches incorporate a programmable timer of either electromechanical or electronic construction, and means for a user to set up manually a desired switching program. With the development of electronic technology, it has become economically viable to provide quite sophisticated programming capabilities in such devices, but in common with most programmable domestic appliances, programming requires a degree of mental application and assistance from instructions which results in the average user not fully exploiting the programming capabilities of the equipment, and rarely reprogramming it once an acceptable program has been achieved, either because of the effort involved, or because the programming instructions are no longer to hand.
Such switches may either take the form of a programmable switching device connected between an outlet and a light or appliance to be controlled, or may replace a conventional switch.
Examples of known programmable light switch controllers may be found in U.S. Pat. Nos. 4,521,843 (Pezzolo), 4,570,216 (Chan) and 4,354,120 (Schornack). The Chan and Schornack patents disclose the concept of a programming mode in which operations of the switch in a 24 hour period following initialization of the switch are memorized and repeated indefinitely. The program can apparently only be altered by resetting the device, or by powering down, i.e. disconnecting and then reconnecting the switch from the circuit in which it is used, followed by complete reprogramming. In practice, this means, that the device cannot be reprogrammed in this mode without first destroying the existing program and then waiting for twenty-four hours.